I started a new game in Pokemon Blue, and I completed the S.S. Anne yesterday. I also recently renewed my Crystal game (just before the Ice Path). I have been trading pokemon between the two games, as your Pokemon are (obviously) stronger if they are traded.

I traded an Eevee I hatched from an Egg to Blue. It started at Level 5, and I was battling it to level up. When it got to level 7, it started evolving, without a stone! Ummm... "what happen?"

I freaked out and hit B before I could see what it was changing to, because I didn't want it to evolve yet. I was totally surprised, because I didn't thinkg Eevee could evolve without a Stone, at least not in RBY!

Has this happened to anyone else? What would be the result if I let it evolve? Is it because my Eevee was the result of Pokemon breeding? I'm totally confused!

What did it evolve into? If it was Espeon or Umbreon, that's because you maximized its happiness. Those evolutions were added in the Generation 2 games (Gold, Silver, and Crystal).

I stopped the evolution from happening by pressing B. I actually hit it right away, so I didn't even get the glimpse of what it would have become when it flashes back and forth.

I know it can evolve into Espeon or Umbreon when it's happy in Gen II and beyond, but this is Pokemon Blue (Gen I)! Very odd. The Eevee was *originally* obtained in Crystal, but I wouldn't think it could evolve into a form that doesn't exist in the Gen I Pokedex.

The Gen II forms aren't even programmed into Red/Blue, so barring a cracked game, it's not possible for it to evolve into them on one of those cartridges. It sounds like some kind of flag was accidentally activated in G/S that are causing it to evolve. Try leveling it again and see what it turns into.

That's strange, but it isn't the first time I've read about a case like this.

When a Pokémon is traded from a GenII game to a GenI game, the happiness stat is lost completely, and it would evolve only to evolutions in the first game. For it to have evolved like this, it is in theory possible that the transfer was interrupted earlier, causing a second ID representation to have been converted into something else, but I didn't /think/ this is how data was stored in any Pokémon game.

In generation one, Pokémon can only evolve by level up and by stones. Metapod (see http://crystal-islands.com/dex/011) and Kakuna (see http://crystal-islands.com/dex/014) both evolve at level 7. If somehow the game is looking up the evolution data for Caterpie or Weedle, then it would have evolved like you described.

At least, this is my best guess. I haven't heard of anything like this.

Looks like it was trying to evolve into Jolteon. I kept at it, and at Level 16 it did the same thing. This time, I kept my finger off the button until I could see the other picture in the evolution scene. It was definitely a Jolteon. I wasn't sure I wanted it, since I only had a split second to think about it. I think I'll let it evolve if it does it again.

Yep, it tried to evolve again at Level 17, so I let it. Now I have a Jolteon without having to use a Thunder Stone!

Jolteon is probably my favorite Eevolution, despite it (Electric) not being one of my favorite types (Grass and Fire), so I guess this is my lucky day!

Amusing. Its not something I've heard of, but it could be just another one of those random glitches that were so common in Red and Blue/Green.

This page may provide clues as to why Eevee evolved without a stone.

http://trsrockin.com/evolutions.html

I heard it from youtube where you can evole eevee without using a stone. I think you got to have a certain pokemon in your 2nd slot and make your eevee evole! Denpending on what certain pokemon you have in your 2nd slot. Like one pokemon will make eevee evole jolten or another will make vaporan. I think this works for any pokemon that needs to use a stone. I'm not too sure about it. I haven't used it.